[PATCH] virtio-net: Fix DMA-from-the-stack in virtnet_set_mac_address()
From: Andy Lutomirski <luto@kernel.org>
Date: 2016-12-06 02:12:00
With CONFIG_VMAP_STACK=y, virtnet_set_mac_address() can be passed a pointer to the stack and it will OOPS. Copy the address to the heap to prevent the crash. Cc: Michael S. Tsirkin <mst@redhat.com> Cc: Jason Wang <redacted> Cc: Laura Abbott <redacted> Reported-by: zbyszek@in.waw.pl Signed-off-by: Andy Lutomirski <luto@kernel.org> --- Very lightly tested. drivers/net/virtio_net.c | 19 ++++++++++++++----- 1 file changed, 14 insertions(+), 5 deletions(-)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 7276d5a95bd0..cbf1c613c67a 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c@@ -969,12 +969,17 @@ static int virtnet_set_mac_address(struct net_device *dev, void *p) struct virtnet_info *vi = netdev_priv(dev); struct virtio_device *vdev = vi->vdev; int ret; - struct sockaddr *addr = p; + struct sockaddr *addr; struct scatterlist sg; - ret = eth_prepare_mac_addr_change(dev, p); + addr = kmalloc(sizeof(*addr), GFP_KERNEL); + if (!addr) + return -ENOMEM; + memcpy(addr, p, sizeof(*addr)); + + ret = eth_prepare_mac_addr_change(dev, addr); if (ret) - return ret; + goto out; if (virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_MAC_ADDR)) { sg_init_one(&sg, addr->sa_data, dev->addr_len);
@@ -982,7 +987,8 @@ static int virtnet_set_mac_address(struct net_device *dev, void *p) VIRTIO_NET_CTRL_MAC_ADDR_SET, &sg)) { dev_warn(&vdev->dev, "Failed to set mac address by vq command.\n"); - return -EINVAL; + ret = -EINVAL; + goto out; } } else if (virtio_has_feature(vdev, VIRTIO_NET_F_MAC) && !virtio_has_feature(vdev, VIRTIO_F_VERSION_1)) {
@@ -996,8 +1002,11 @@ static int virtnet_set_mac_address(struct net_device *dev, void *p) } eth_commit_mac_addr_change(dev, p); + ret = 0; - return 0; +out: + kfree(addr); + return ret; } static struct rtnl_link_stats64 *virtnet_stats(struct net_device *dev,
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2.9.3